Both me and my wife have lost family to cancer. Lung, breast, heart.. you name it.
My wife was diagnosed with Breast Cancer 2 years ago, in Jan 07. Luckily, they caught and removed it before it spread further. She still had to go through Chemo, and radiation. Because it was a particularly aggressive cancer, they hit her with the drugs and radiation faster than they normally do. She had some fairly bad burns from the radiation you can still see today, and of course she lost her hair. She was 28. She hasn't had a re-occurance yet, but it's something that goes through your mind every day, with every new test, with every new mammogram.
She now has a condition called dermatomyacitis, which basically is a skin/muscle condition that was either brought on by the cancer, or is a pre-cursor to the cancer coming back.
Obviously, the doctors can't tell which.
Anyway, we sign up every year for the local Relay for Life.. I recommend it for people even if they don't know someone with cancer.. chances are at some point in your life.. you will.
As people have said before me, it is an atrocious disease.